Resetting Casio G Shock requires great skills because it can end in ruining the watch or losing the screws. If you want to reset Casio because of changing the battery. First of all, I’ll recommend the User manual for Casio watch module because you’ll just need the module number. it is a series of 4 digits engraved on the case back, within a small square. This will provide you with a manual for the exact watch.